Every cause needs its warriors and its diplomats. The human rights and equality campaigner Clare Cozens, who has died aged 45 of a pulmonary embolism, was a rare example of both. In 2007, Clare became special adviser to Ruth Kelly, then the communities and local government secretary, and helped shape the Discrimination Law Review (DLR), which laid the foundations for the Equality Act 2010. When it comes into force in October, the act will simplify three decades' worth of anti-discrimination legislation, extend protection to a wide range of groups that face discrimination and improve public services.

The DLR green paper published in 2007, much of it written by Clare, looked at opportunities to streamline legislation, as well as to extend protection to those left behind by previous waves of reform. For example, she considered effective ways in which to tackle age discrimination outside employment, including in areas such as the health service.

Clare was born in Brentwood, Essex. Her political life began when she was a teenager in the late 1970s, delivering Labour party election leaflets. She attended Shenfield high school, Essex, and during the holidays visited the House of Commons, where her mother, Audrey, worked as a research assistant for a Labour MP. Clare's father, Roger, was a project manager at the National Coal Board.

At 18, Clare stood for election as a local councillor in the most Conservative ward in Brentwood district council. Despite the odds, Clare doubled the Labour vote, probably because so many people had met her face to face. During her gap year, she worked at Basildon's supplementary benefits office, where she helped people to apply for grants and to appeal against decisions.

Clare obtained a BA in jurisprudence from Worcester College, Oxford. As a trainee barrister, she was very active in the Free Representation Unit, which helps people who cannot afford legal representation in employment and social security tribunals. It was there that she met Declan O'Dempsey whom she married in 1991.

Between 1987 and 1988, Clare trained as a barrister at the Inns of Court School of Law in London, which she followed up with several policy and political research roles, including five years spent as a political researcher in the House of Lords' opposition whips office.

From 1998 to 2001, Clare was special adviser to Lady Jay of Paddington, the leader of the House of Lords and minister for women. It was in this influential role that Clare made important contributions to the debate surrounding Lords reform, which culminated in the House of Lords Act 1999 and the removal of the right of several hundred members of the Lords to inherit their seats. Her tenacity prompted the Daily Mail to describe her as "formidable" and report that she had earned the nickname "La Tricoteuse".

This amused her, and was at odds with the personable, warm and generous Clare who sold homemade jams and cakes to raise money for charity. (She was a talented chef who made it to the final pre-TV heat of Masterchef and she also ran her own catering business.) But as I know, having seen her in action, Clare was a tough, effective and pragmatic political operator.

Following her work on the Discrimination Law Review, she spearheaded the considerable task of producing the Equality and Human Rights Commission's guidance on the Equality act, which aimed to explain people's rights and responsibilities under the new legislation and make it simpler and easier for people, both individuals and employers, to understand.

Clare was always passionate about music. She had joined the junior choir at St Mary's Church, Shenfield, and sang in choirs throughout her life, including the Parliament choir. Combining her interests in music and social justice, she volunteered for 20 years with the Camberwell Choir School, transforming it into a key local charity, which gives children in south London the chance to learn a musical instrument.